Synthesis and structural characterization of CO 2 -soluble oxidizers [Bu 4 N]BrO 3 and [Bu 4 N]ClO 3 and their dissolution in cosolvent-modified CO 2 for reservoir applications.

CO 2 utilization in upsteam oil and gas applications requires CO 2 -soluble additives such as polymers, surfactants, and other components. Here we report the facile synthesis of CO 2 -soluble oxidizers composed of judiciously selected organic cations paired with oxidizing anions. [Bu 4 N]BrO 3 and [Bu 4 N]ClO 3 are prepared using a double displacement synthetic strategy, whereby the crystalline product is readily obtained in high yield and structurally characterized using single-crystal X-ray diffraction. The facility of the approach is demonstrated through the preparation of several additional alkylammonium bromate compounds. Static solubility studies using a high-pressure cell with viewing windows showed that tetrabutylammonium compounds could be solubilized using cosolvent-modified CO 2 . Using 4 mol% ethanol as cosolvent, >3 mM [Bu 4 N]BrO 3 could be dissolved in CO 2 , while ∼0.75 mM [Bu 4 N]ClO 3 could be dissolved in the same solvent system. The solubility properties of [Bu 4 N]BrO 3 along with its thermal stability up to ∼200 °C suggest that it is a promising oilfield oxidizer that can be utilized in subterranean CO 2 applications.